To facilitate accurate focussing of the fundus camera, one or more marks may be projected onto the eye fundus and the image of these marks may then be observed though the fundus camera. Further, split prisms may be provided within the line projection system such that the image of the projected marks on the eye fundus appears as a split line if the camera is not correctly focussed, as discussed in U.S. Pat. No. 3,925,793. The optical components for such a system for projecting a mark to aid focussing may be separate from the illumination system and combined with an afocal lens system, such that the focus of the viewing system and the focal plane of the projected line system may be maintained coincident as the focus of the viewing system is adjusted as discussed in U.S. Pat. No. 4,187,014. The afocal lens system required for this system has a disadvantage that the magnification of the image appearing at the camera imaging plane changes through a large range as the focus is adjusted and this varies the area of the fundus and the apparent brightness of the image through a large range. Alternatively, the optical components for such a system for projecting a line to aid focussing may be separate from all or part of the focussing and illumination systems and these optical components may be moved by cams or linkages or similar means such that the focus of the viewing system and the focal plane of the projected line system may be maintained coincident as the focus of the viewing system is adjusted as discussed in U.S. Pat. No. 4,436,388. This alternative allows the use of a lens of reduced or negative power as the focussing lens with a result that the change in image magnification is reduced, but the required cams or linkages increase the mechanical complexity of the system.